Question

Which of the following properties of water can be used to explain the spherical shape of rain droplets?

• A. Viscosity
• B. Surface tension
• C. Critical phenomenon
• D. Vapour pressure

Answer 1

The correct option is B Surface tension

The spherical shape of rain droplets is due to lowest surface tension of sphere. The lowest energy state of any liquid will be when its surface area is minimum. Hence it tries to decrease the surface area of the liquid to a minimum value. When a drop is formed, upward thrust due to surface tension balances the gravitational force.
$2\pi r\gamma =mg$, where r and m are radius and mass of spherical droplet respectively and g is accelearation due to gravity.